Conventional input devices, such as, for example, a keyboard, a mouse, or a single-point touch screen, were designed for a computing world primarily oriented toward textual based input methods and having limited utility in a graphical computer programming environment. These conventional input devices have drawbacks. A keyboard can lead to repetitive stress injury. A mouse can only operate on a single point on the display and typically contains only two to three buttons of limited usability. A single-point touch screen can only register one point of contact at a time. These conventional input devices are not operated in an intuitive fashion and may require significant training before they can be effectively operated. For example, users of graphical models may find conventional input devices to be unintuitive and/or inadequate to allow the users to efficiently perform desired interactions with graphical models.